Spiders

DOE Cayman Islands

Spiny-backed Orb Weaver. (Gasteracantha cancriformis) – Not Dangerous

The Cayman Islands supports many species of spiders. Many species are likely still to be discovered.

Most spiders are harmless to humans; however there are several species of spiders in the Cayman Islands which are potentially harmful. Being able to identify these species is a useful skill.
 
 

When it comes to “dangerous” spiders:

  • “Poisonous” is not a term which is applied to spiders (snakes or scorpions).
  • “Poisonous” is a term which applies to something which is toxic if inhaled or eaten, such as a toadstool or a poisonous berry.
  • “Venomous” is the correct the term for an animal which can introduce a toxin in the form of a sting or a bite, such as a spider.

 

The bites of almost all spiders are venomous; however most spider venoms have little or no effect on humans. Venoms are species-specific. This means venoms are toxic to some species and not toxic to others. Some spider venoms which are harmless to people are toxic to pets. Some venoms which effect cats do not effect dogs, and vice-versa.

When dealing with spider bites, several factors are important:

  1. SPECIES OF SPIDER: Spider venoms vary greatly between different species of spiders, and so do the corresponding medical treatments. If you are bitten by a spider and wish to seek medical treatment, if possible, every effort should be made to catch the spider (fairly intact), in order to assist medical staff with identification.
  2. AGGRESSION: Some spiders are more aggressive than others. Some of the most venomous spiders are extremely docile, making bites extremely rare (even when the spiders themselves are very common).
  3. DELIVERY: The amount of venom injected in an individual bite can vary. Additionally, the bites of some spiders are limited by physical attributes. For example, spiders with small teeth may not be able to penetrate clothing or even human skin.
  4. SUSCEPTIBILITY: As with most venoms, some individuals will be more susceptible than others. The elderly and infirm, and the very young are the most susceptible to spider bites. Babies in particular are susceptible to vemons, due to their small body size. Reactions to venoms also varies between individuals.
  5. INFECTION: If treated inappropriately, even a benign cut or insect bite can easily become infected. Neglected cuts and bites which have been allowed to become infected are often mistaken for venomous spider bites. All wounds should be cleaned appropriately. Care should be taken not to scratch wounds, or introduce dirt or bacteria. Infected wounds can be potentially life-threatening.

Brown Recluse (Loxosceles reclusa)
brownrecluseThe Brown Recluse or Violin Spider Loxosceles reclusa is small, brown and unremarkable in appearance (see image below). It can be identified by the small, dark violin shape (from which it takes its name), situation on the top of the thorax (see image above).

Recluse spiders build irregular, disorderly webs, often in woodpiles and sheds, closets, garages, and other places that are dry and generally undisturbed. In houses, they often favor cardboard – they have also been encountered in shoes, inside dressers, in bed sheets, in clothes stacked or piled or left lying on the floor, inside work gloves, behind baseboards and pictures, and in toilets.

As suggested by its name reclusa (recluse), the Brown Recluse is rarely aggressive. The fangs of the brown recluse are tiny, so they are unable to penetrate most fabric. The spider usually bites only when pressed against the skin, such as when tangled within clothes, towels, bedding, inside work gloves, etc. Many human victims report having been bitten after putting on clothes that had not been worn recently, or had been left for many days undisturbed on the floor.

The bite frequently is not felt initially and may not be immediately painful, but it can be serious. The bite produces a mild stinging, followed by local redness and intense pain within eight hours. A fluid-filled blister forms at the site and then sloughs off to leave a deep, enlarging ulcer. The brown recluse bears a potentially deadly hemotoxic venom. Most bites are minor with no necrosis; however, a small number of bites do produce severe necrosis. A smaller number produce severe cutaneous and systemic symptoms.

Brown Widow (Latrodectus geometricus)
brownwidowThe Brown Widow Latrodectus geometricus is fairly common in the Cayman Islands. The body colour is variable, from tan to dark brown and black. Like its more famous cousin, the Black Widow, the Brown Widow has a prominent hourglass-shaped marking on the underside of the abdomen; the brown widow’s hourglass, however, is usually a orange or a yellowish color, rather than red. The easiest way to distinguish a Brown Widow from a Black Widow is by the appearance of the egg sac. The Brown Widow has a spiky egg sac, shapped like a sandspur, a grass burr, or the head of a medieval mace.

The symptoms of Brown Widow bites generally seem to be less severe than those of Black Widows. There is some debate as to whether the vemon of Brown Widows is less toxic than that of Black Widows, or whether it is simply a matter that they inject less venom. First aid involves the application of an ice pack to control inflammation, and prompt medical care. If it can be easily captured, the spider should be brought with the patient in a clear, tightly closed container so it may be identified.

Black Widow (Latrodectus mactans)
blackwidowBlack Widows Latrodectus mactans are related to Brown Widows, and closely resemble them in appearance, though Black Widows are generally darker (black) in appearance. Both spiders have an hourglass shape on the underside of the body. In the case of the Black Widow, this is generally bright red.

Black widows can also be distinguised from Brawn Widows by the shape of their egg-sac, the surface of which is smooth, unlike the spiky surface of the egg sac of the Brown Widow. Although serious, a Black Widow bite is rarely lethal. The bite feels like a pinprick. The victom may not even realise that they have been bitten. First symptoms are generally light swelling and faint red marks. Within a few hours, though, intense pain and stiffness begin. Other signs and symptoms include chill, fever, ausea and vomitin and severe abdominal pain.

 
 

Tarantula (Theraphosidae)
tarantulaCayman plays host to at least one species of tarantula, (appearing similar to the one in the image above). While tiny in comparison with most Tarantulas, with a body diameter of a little over a centimeter, the species found in the Cayman Islands is still constitutes a good-sized spider, albeit resembling a perfect miniature version of more familiar species.

Tarantulas have large jaws and so have the potential to inflict a bite which may be physically painful, but not toxic. Like most Tarantula species, the Cayman tarantula is fairly docile and can be handled with appropriate care.

Many tarantula species have the capacity to eject irritant hairs from their bodies. This can cause irritation to the skin, however, these hairs can cause a serious problem if they get into the eyes. For this reason, when handling tarantulas, they should always be kept well away from the eyes and face.

First Aid for Spider Bites

If bitten by a spider:
firstaidIdentify the spider. Always try to identify the spider which bit you. There are many similar species of spiders, and confusion of species can happen easily. If possible, catch the spider in a clear container – one which can be securely closed. The spider should accompany the victim when medical attention is sought. This will enable medical workers to identify the spider as necessary.

  • Cleanse the wound. Use soap and water to clean the wound and skin around the spider bite.
  • Slow the spread of venom. If the spider bite is to an arm or a leg, tie a snug bandage above the bite and elevate the limb to help slow or halt the venom’s spread. Ensure that the bandage is not so tight that it cuts off circulation.
  • Use a cold cloth at the bite location. Apply a cloth dampened with cold water or filled with ice to reduce inflammation.
  • Seek immediate medical attention. Treatment for the bite of a black widow may require an anti-venom medication. Doctors may treat a brown recluse spider bite with various medications.

Scorpions

Scorpions-copy-1024x768small

Dangers

There are no recorded deaths from scorpions in the Cayman Islands, however all scorpions should be treated with respect as their stings can be very painful.

Scorpion stings present the greatest danger to the elderly and infirm, and to the very young. Small children and babies are most susceptible to the effects of venom. Rather in the way that some people are allergic to bee stings, some people can also display an adverse reaction to scorpion stings.

Venom

Scorpions deliver a sting from a barb located at the end of their tails. Scorpion venom is designed to immobilize and kill prey species (beetles, crickets, roaches, worms and other invertebrates), but the mixture of compounds in scorpion venom can also cause problems for none-prey species (such as humans, cats and dogs), if they are stung.

The amount of venom injected by a strike varies greatly, even within successive strikes from the same individual. Many strikes are “dry strikes” in which no venom is injected at all. This means that, if you are stung by a scorpion, it is difficult to know how much venom you have received, if any.





Sting Sypmtoms

Symptoms of a scorpion sting will vary from person to person. In general, however, the first sensation will be a short, sharp pain from the stab of the barb. If venom is injected, this may be followed by spreading feelings of pain and numbness around the affected area. A feeling of swelling, tightness and burning may be experienced, along with some inflammation spreading out from the affected site. Numbness in the lips and tip of the tongue (similar to the sensation of a dental injection) may also be experienced. Symptoms may last for a about an hour.

In the case of more severe reactions, systemic symptoms may arise: flushing, hypertension and wheezing, respiratory difficulty, neuromuscular dysfunction and cranial nerve dysfunction.

  1. Identify the scorpion. Always try to identify the scorpion which stung you. Confusion of species can happen easily. If possible, catch the scorpion in a clear container – one which can be securely closed. The scorpion should accompany the victim when medical attention is sought. This will enable medical workers to identify the scorpion as necessary.
  2. Cleanse the wound. Use soap and water to clean the wound and skin around the sting.
  3. Slow the spread of venom. If the sting is to an arm or a leg, tie a snug bandage above the bite and elevate the limb to help slow or halt the venom’s spread. Ensure that the bandage is not so tight that it cuts off circulation.
  4. Use a cold cloth at the bite location. Apply a cloth dampened with cold water or filled with ice to reduce inflammation.
  5. Seek medical attention. Treatment for the bite of a black widow may require an anti-venom medication. Doctors may treat a brown recluse spider bite with various medications.

If symptoms are mild, and you prefer to self-treat:

    • Acetaminphen (Tylenol) 1-2 tablets will relieve pain (standard dosage). Avoid aspirin and ibuprofen.
    • Do not cut into the wound or apply suction.
    • Seek help if symptoms persist or worsen.

 





Habits and Habitats

Scorpions are nocturnal and prefer dry areas. They are attracted to narrow cracks and crevices. In the wild their habitat includes the spaces under stones, and beneath peeling bark. They will often emerge en-masse in the event of heavy rains and flooding, in search of dry ground.

Scorpions are naturally attracted to narrow spaces, and this propensity also attracts scorpions to man-made environments: wood piles, under plant pots, door jams, the undersides of drawers, between books, behind pictures and shelving, inside piles of laundry, folded towels, and under bed sheets.

Scorpions are adept climbers and can easily scale a tin guttering to gain access to a house through a hole in the roof or missing soffit. The gaps beneath doors are also a favored means of entry into homes.

Discouraging Scorpions

Once scorpions are inside you house, they can be difficult to locate and control, so prevention is better than cure.

Ensure you house is in a good state of repair. Replace missing roof tiles and broken soffits. Ensure doors are well-fitting and use brush guards or rubber guards to plug gaps around the frames. Do not leave your doors open unnecessarily, especially during heavy rain.

If you keep a woodpile or plant pots, try to move them some distance from your doorway.